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If you take your time to do the research FIRST, you can successfully set-up and keep ANY type of aquarium with ease."Not using a quarantine tank is like playing Russian roulette. Nobody wins the game, some people just get to play longer than others." - Anthony CalfoFishless CycleCycling with FishMarine Aquarium Info [URL="http://saltwater.aquaticcommunity.com/"]

Just hold the razor at a ~45D and go slow. If you are careful you can take all the paint off without a scratch.

If you take your time to do the research FIRST, you can successfully set-up and keep ANY type of aquarium with ease."Not using a quarantine tank is like playing Russian roulette. Nobody wins the game, some people just get to play longer than others." - Anthony CalfoFishless CycleCycling with FishMarine Aquarium Info [URL="http://saltwater.aquaticcommunity.com/"]

Well, I've run into a problem with that hole in the back. Even the smallest PVC pipe I've found (1/2 an inch) won't fit. Looking online, I think this was meant for a 3/8ths inches pipe, but I can't find any such things locally.

The problem may be that this aquarium was apparently custom built in Holland and I think uses a metric standard. Is there anything else I could do? Maybe silicone some alternative?

I wouldn't chance it... the problem is when you try and get silicon to bond to something flexible it just won't seal as well... I'd go ahead and drill the hole out so it's bigger and you can fit whatever size drain pipe you'd like on there

55g Long --> After 18mo of doing well the tank crashed during moving. Most likely cause: Flatworm Die-off... won't start another until after moving... Likely not until late 2013

If all you can put in the tank is a 3/8" bulkhead flange, then I would not even bother using that hole for anything. A 3/8" line would only give you ~400 gph assuming you use it for your return line from your sump. That would be about 1/2 to 1/3 of the total flow you would need (IMO) going through your sump.

I would suggest either seal it, or get it drilled to fit a 1" bulkhead flange.

If you take your time to do the research FIRST, you can successfully set-up and keep ANY type of aquarium with ease."Not using a quarantine tank is like playing Russian roulette. Nobody wins the game, some people just get to play longer than others." - Anthony CalfoFishless CycleCycling with FishMarine Aquarium Info [URL="http://saltwater.aquaticcommunity.com/"]